类和对象（2）

实验4：

Complex.hpp文件源码

#pragma once

// Complex类的定义
#include <iostream>

using namespace std;

// Complex类的声明
class Complex {
public:
    Complex(double r = 0.0, double i = 0.0);
    Complex(const Complex& obj);
    double get_real()const { return real; }
    double get_imag()const { return imag; }
    void show() const;
    void add(Complex c);

private:
    double real;
    double imag;

public:
    friend Complex add(Complex c1, Complex c2);
    friend bool is_equal(Complex c1, Complex c2) ;
    friend double abs(Complex c);
};

// 函数定义
Complex::Complex(double r, double i) {
    real = r;
    imag = i;
}

Complex::Complex(const Complex& obj) : real{ obj.real }, imag{ obj.imag }{
}

void Complex::show()const {
    if (imag < 0)
        cout << real << " - " << -imag << "i";
    else {
        if (imag == 0)
            cout << real;
        else
            cout << real << "+" << imag << "i";
    }
}

void Complex::add(Complex c) {
    real += c.get_real();
    imag += c.get_imag();
}

Complex add(Complex c1, Complex c2) {
    Complex c;
    c.real = c1.real + c2.real;
    c.imag = c1.imag + c2.imag;
    return c;
}

bool is_equal(Complex c1, Complex c2) {
    if (c1.real == c2.real && c1.imag == c2.imag)
        return right;
    else
        return false;
}

double abs(Complex c) {
    return sqrt(c.real * c.real + c.imag * c.imag);
}

task.cpp文件源码

#include "Complex.hpp"
#include <iostream>

// 类测试
void test() {
    using namespace std;

    Complex c1(3, -4);
    const Complex c2(4.5);
    Complex c3(c1);

    cout << "c1 = ";
    c1.show();
    cout << endl;

    cout << "c2 = ";
    c2.show();
    cout << endl;
    cout << "c2.imag = " << c2.get_imag() << endl;

    cout << "c3 = ";
    c3.show();
    cout << endl;

    cout << "abs(c1) = ";
    cout << abs(c1) << endl;

    cout << boolalpha;
    cout << "c1 == c3 : " << is_equal(c1, c3) << endl;
    cout << "c1 == c2 : " << is_equal(c1, c2) << endl;

    Complex c4;
    c4 = add(c1, c2);
    cout << "c4 = c1 + c2 = ";
    c4.show();
    cout << endl;

    c1.add(c2);
    cout << "c1 += c2, " << "c1 = ";
    c1.show();
    cout << endl;
}

int main() {
    test();
}

task4运行截图

 

 

 

task5：

User.hpp文件源码

#pragma once
#include <iostream>

// User类的定义

using namespace std;

// User类的声明
class User {
public: 
    User(string name0, string passwd0 = "111111", string email0 = " ") :name { name0 },
    passwd{ passwd0 }, email{ email0 } { n++; }
    ~User() { n--; }

    void set_email();
    void change_passwd();
    void print_info();
    static void print_n();   // 静态成员函数

private:
    string name, passwd, email;
    static int n;       // 静态数据成员声明，用于记录用户的个数
};

int User::n = 0;    // 静态数据成员定义和初始化，使用类名限定

// 函数定义
void User::set_email() {
    cout << "Enter email address: ";
    cin >> email;
    cout << "email is set successfully...\n";
}

void User::change_passwd() {
    int i = 1;
    cout << "Enter old passwd: ";
    while (i <= 3) {
        string s1;
        cin >> s1;
        if (s1 == passwd) {
            cout << "Enter new passwd: ";
            cin >> s1;
            passwd = s1;
            break;
        }
        else {
            cout << "passwd input error. ";
            if (i == 3)
                cout << "Please try after a while." << endl;
            else
                cout << "Please re-enter again: ";
            i++;
        }
    }
}

void User::print_info() {
    int len = passwd.size();
    string s2( len, '*' );
    // passwd.assign(passwd.size(), '*');     // 重新赋值
    cout << "name:   " << name << endl;
    cout << "passwd: " << s2 << endl;
    cout << "email:  " << email << endl;
}

void User::print_n() {
    cout << "there are " << n << " users.";
    cout << endl;
}

task5.cpp文件源码

#include "User.hpp"
#include <iostream>

// 测试User类
void test() {
    using std::cout;
    using std::endl;

    cout << "testing 1......\n";
    User user1("Jonny", "92197", "xyz@hotmail.com");
    user1.print_info();

    cout << endl
         << "testing 2......\n\n";

    User user2("Leonard");
    user2.change_passwd();
    user2.set_email();
    user2.print_info();

    cout << endl;
    User::print_n();
}

int main() {
    test();
}

task5运行截图

 

 

 

 

 

实验总结：

1、在Complex.hpp的创建过程中，直观感受到了const关键字对于成员函数的限制性，以及在调用参数时产生的一些报错，对于const的理解与运用更加熟练。

2、在User.hpp的创建过程中，主要是对于在密码加密输出那几行代码琢磨了很久，对于string类的相关函数的使用还是不够熟练。

3、task5的选做部分，emmm，还没有太清楚的思路和想法，后续再看。